Internal-combustion engine



April 17. 1928.

r W. W. MARVIN INTERNAL COMBUSTION ENGINE Filed March 4, 1927 2 Sheets-Sheet 1 INVENTOR.

1 {I 4 v 1 Z MM (o. b)

ATTORNEY.

W. W. MARVIN INTERNAL COMBUSTION ENGINE Filed March 4, 1927 2 Sheets-Sheet IN V EN TOR.

ATTORNEY.

Patented Apr. 17, 1928.

WARD V. MARVIN, 0F ROYAL OAK, MLCHIGAN.

INTERNAL-COMBUSTION ENGINE.

Application filed March 4, 1927. Serial no. 172,521.

The present invention relates to internal combustion engines and particularly to en,- gines of the two-stroke cycle't-ype.

Heretofore in engines of this type it has been customary to introduce the charge into the cylinder after previous compression in the crankcase. This operation usually interferes both with lubrication of the engine and with the proper combustion of the charge. Other. schemes to overcome the difficulty have been proposed and among these the step piston. But none have proven very satisfactory in actual use.

Among the objects of the present invention is to overcome these objections and produce an engine which involves neither crankcase compression nor step piston construction and which prepares a clean, properly combustible charge and delivers it to the cylinder in condition to obtain maximum results therefrom.

Other objects will readily appear to those skilled in the art upon reference to the following description and accompanying drawings, in which F ig. 1 is avertical section through one cylinder of my improved engine;

Fig.2 is a horizontal section on line 22 of Fig. 1;

Fig. 3 is a vertical section with parts in elevation taken at right angles to Fig. 1;

Fig. 4 is a horizontal section on line 44 of Fig. 3.

As indicated in the drawings, the engine consists of one or more cylinders 10, which may be water-jacketed as shown, mounted on a crankcase 11 as by cap screws 12. The cylinder will be provided with the usual spark plug 13, preferably in the center of thehead. At one side, near the extreme lower limit of piston travel. is an exhaust outlet 14 connected to an exhaust manifold 15 and diametrically opposite said exhaust is an inlet 16 which connects with a small chamber 17 which in turn is connected at its lower end through an opening or openings 18 with the interior of the cylinder, forming a conduit connecting the compression and firing chambers.

The piston 20, adapted to reciprocate in the cylinder 10, is finished both inside and out and provided on the outside near the head with packing rings 21, the head being provided with a deflector 22 adapted to deflect incoming gases toward the top of the cylinder. Piston is provided with a skirt 23 which is continuous for a length equal to about the distance of its travel and below this length 'is' provided with wide diametrically located notches 24. The two legs formed by the notches furnish convenient means 'for attachment of the piston to a piston rod 30. The latter is preferably in two upwardly extending parts bolted to piston 20 and is in turn secured to or formed integral with a scotch yoke 31. The yoke 31 coacts with a sliding block '32 mounted upon the crank bearing 33 of a crankshaft 34. The yoke 31 preferably is guided in guides 35 in the sides of the crankcase 11.

Extending up within cylinder 10 and piston 20 is a stationary piston head 40, provided with packing rings 41 to make a gas compression fit in piston 20, which latter will be roperly finished inside for this purpose. iston head is supported by two legs 42 and 43, secured to or formed integral with the upper portion of crankcase 11. Leg 42 may be made hollow for lightness. Leg 43 is also hollow and open at its lower end to connect with an intake manifold 44. The upper end of leg 43 is expanded and the piston head 40 formed thereon.

Piston head 40 is provided with av central opening 45 in which operates a, valve 46. The stem 47 of the latter extends down between the legs 42 and 43 and is provided with a spring 48 adapted to hold the valve on its seat or return it from opened position.

Manifold 44 will be connected to the usual carburetor.

The engine operates on the two stroke cycle principle. When the piston ascends a charge will be drawn in through manifold 44, leg 43 and valve 46. When the piston descends the charge will be compressed until the opening 50 in the piston wall registers with opening 18. The compressed charge will then pass through the latter, chamber 17 and opening16 into the firing chamber above piston 20, being deflected upward by deflector 22. In the meantime, port 14 has been open to allow escape of burned gases from a previous combustion and the residue ofthat charge is forced out by the incoming charge.

It is particularly desirable to arrange the compression chamber within piston 20 as this permits absorption of. considerable heat of combustion by the gases therein and in contact with the underside of the piston head. Further, elimination of crankcase compression also eliminates the lubrication and other troubles caused thereby.

It is also particularly desirable to combine the form of piston shown with the form of connecting rod shown as such combination permits the fitting of the piston in the cylinder with considerable clearance and the substantial elimination of contact between the piston proper and cylinder walls, the yoke 31 guided in the crankcase, permitting the floating of piston 20 between rings 21 and 41 and compelling a rectilinear movement of the rod and piston 20. c

Having now described the invention and the preferred form of embodiment thereof, it is to be understood that the said invention is to be limited not to the specific details herein described and illustrated but only by the scope of the claim which follows.

I claim i In an internal combustion engine of the two-stroke cycle type, a oylinderhaving a piston reciprocable therein, a stationary piston head mounted within said piston and provided with an intake valve, supporting means for said head including an intake conduit, packing rings for said piston and for said head, a conduit connecting the interior of the piston above said head and the cylinder above said piston when the latter is in its lowest position, a forked skirt on said piston, a divided piston rod fixed to the piston and adapted to actuate a crankshaft, and means for compelling a rectilinear movement of said rod and piston, said forked piston and divided piston rod providing an opening for the passage therethrough of said supporting means.

NAB-D W. MARVIN. 

